The U.S. Census Bureau said Friday it won't be delivering data used for redrawing congressional and state legislative districts until the end of September, causing headaches for state lawmakers and redistricting commissions facing deadlines to redraw districts this year.

Officials at the statistical agency blamed operational delays during the 2020 census caused by the pandemic.

“The biggest reason? COVID-19. It's something beyond the Census Bureau's control," said Kathleen Styles, the Census Bureau's chief of Decennial Communications and Stakeholder Relations, in a call with reporters.

Styles had previously said the redistricting data would be available no earlier than the end of July because of delays caused by the virus. Before the pandemic, the deadline for finishing the redistricting data had been March 31.

The redistricting data includes counts of population by race, Hispanic origin, voting age and housing occupancy status at geographic levels as small as neighborhoods, and they are used for drawing voting districts for Congress and state legislatures. Unlike in past decades when the data were released to states on a flow basis, the 2020 redistricting data will be made available to the states all at once, according to the Census Bureau.

The delayed release creates a chain reaction in the political world. Several states will not get the data until after their legal deadlines for drawing new districts, requiring them to either rewrite laws or ask courts to allow them a free pass due to the delay. Candidates may not know yet whether they will live in the district they want to run in by the filing deadline. In some cases, if fights over new maps drag into the New Year, primaries may have to be delayed.

In the end, though, experts said the elections will proceed as normal in November 2022. The biggest impact will be to compress the window during which lawyers can challenge bad maps in court.

“It makes it significantly more likely that courts will bump up against election deadlines,” said Michael Li of the Brennan Center for Justice.

Census Bureau officials are aware of the deadlines facing lawmakers and redistricting commissions nationwide, but “we have a strong schedule that reflects the time we need," said James Whitehorne, chief of the Redistricting and Voting Rights Data office at the bureau.

“We are consistently aware of the urgency and needs of the states for this data," Whitehorne said.

Gail Gitcho, a spokeswoman for the National Republican Redistricting Trust, said the group's attorneys were reviewing the implications of the delay.

Eric Holder, a U.S. attorney general in the Obama administration, warned that the new deadline shouldn't be “a pretext to hold 2022 elections on old maps" in an effort at political gain, or to draw maps without significant public input, using the compressed timetable as an excuse.

“I will oppose any such efforts," said Holder, who chairs the National Democratic Redistricting Committee.

In Pennsylvania, the state Senate’s ranking member, President Pro Tempore Jake Corman, said late-arriving data could mean postponement of next year’s primary election, currently set for May 17, 2022. The state House and Senate will hold a joint committee hearing Wednesday on the impact of the delay in the Census Bureau data.

The announcement from the statistical agency came as a bipartisan group of U.S. senators introduced legislation that would extend the deadline for turning in the redistricting data to Sept. 30.

The legislation introduced by Democratic U.S. Sen. Brian Schatz of Hawaii and Republican U.S. Sens. Lisa Murkowski and Dan Sullivan, both of Alaska, also sets an April 30 deadline for turning in the apportionment figures used for divvying up congressional seats among the states. The Census Bureau had previously announced it was aiming to hand in those state population counts by that date.

The once-a-decade census is used to determine how many congressional seats and Electoral College votes each state gets. It also is used for redrawing state and local political districts and determining the distribution of $1.5 trillion in federal spending each year.

The deadline for turning in the apportionment numbers used for congressional seats has been a moving, and litigated, target since the coronavirus pandemic upended the Census Bureau’s head count of every U.S. resident. The numbers were supposed to be turned in at the end of last year, but the Census Bureau requested until the end of April after the virus outbreak caused the bureau to suspend operations.

Bureau officials say they need the extra time to fix not-unexpected irregularities found in the data.

The lawmakers introduced similar legislation last year but it never went anywhere in the Republican-controlled Senate after identical legislation passed the Democratic-controlled House. By then, the Trump administration had switched back to a Dec. 31 deadline for finishing the apportionment data after President Donald Trump issued a directive seeking to exclude people in the U.S. illegally from the numbers used for divvying up congressional seats.

President Joe Biden rescinded Trump’s order on his first day taking office last month. Control of the Senate also is now evenly split between Democrats and Republicans, with Vice President Kamala Harris able to provide a deciding vote for the Democrats.

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AP writer Nicholas Riccardi in Denver and Marc Levy in Harrisburg, Pa. contributed to this report.

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Follow Mike Schneider on Twitter at https://twitter.com/MikeSchneiderAP